I did a thing a while ago (previous computer, pre-blockland times back when I hung out on the Stabyourself.net forums)
I believe my restrictions were:
pallete is shown (I think it was some atari or commodore thing? it's on wikipedia and I think it's not NES because that would be dumb of me to use such an overused palette)
5 colors per 16x16 space,
plus black, which cannot be changed and doesn't count toward the limit. Thought it was three but the pipes have FIVE COLORS wow too hi-tek for me not retro enough.
I had lots of plans to expand it and plan to make something with a different palette and more restrictive restrictions. Say, a four-color thing, or three.
Those of you who haven't worked with palettes and restrictions and such I recommend it, it makes it look more retro and accurate.
I eventually converted the image to a Mari0 tileset using a nifty program I wrote specifically for converting the 18x18 square with 1px border format into a 16x16 no border and then someone else's python script that turns seamless images into the 17px 1px border on right and bottom format Mari0 uses.
(Mari0 is SMB with portals for those who haven't seen that marvel of a game.)
